Protective clothing articles used for wear in wet conditions (such as rain, snow, etc.); in outdoor activities (such as skiing, biking, hiking, etc.); in handling hazardous chemicals, in preventing contamination, in avoiding infection, should in each instance protect the wearer by preventing leakage of water or other fluids and microorganisms into the article while keeping the wearer comfortable by allowing perspiration to evaporate from the wearer to the outside of the article. In addition, if such an article is intended to be reusable, it should maintain the functional attributes of protection and comfort during ordinary use including automatic machine washing.
In protective clothing articles where flexibility of movement is essential, stretchable fabric laminates with the above functional attributes are needed along with soft and drapeable feeling. Such stretchable fabric laminates are increasingly being used to make protective clothing articles which are form-fitting since the stretch properties of the material allow for a closer fit without adversely affecting the wearer's comfort. Gloves, mittens, socks, stockings, ski wear, running suits, athletic garments, medical compresses, are some examples of such articles of protective clothing requiring form-fitting characteristics.
In addition to the above, the direction or directions of stretch, the amount of stretch and its recovery and the force exerted during recovery are all important properties that determine comfort of form-fitting articles of protective clothing as well as the method and ease of manufacturing them. The precise magnitude and balance of these properties in a stretchable fabric material, however, depend on each specific end use.
A variety of laminated fabrics are known which offer stretch characteristics in addition to waterproofness and breathability as measured by their ability to pass water vapor. U.S. Pat. No. 4,935,287 (Johnson et. al.) describes stretchable laminate constructions based on an elastic fabric and a substantially non-elastic film which are held in intimate contact with one another by means of a noncontinuous pattern of adhesive. When the laminate constructions of the invention are in a relaxed state, the length of the film between adjacent adhesion points in the direction of stretch of the elastic fabric is essentially equivalent to the length of the elastic fabric between the same adhesion points when the construction is extended to its elastic recovery limit. A preferred embodiment of the invention utilizes waterproof breathable non-elastic membranes to produce laminate constructions suitable for clean room and protective garment applications. The breathable material of this invention provides stretch properties only in the machine direction.
U.S. Pat. No. 5,244,716 (Thornton et. al.) describes a composite extendable material useful for making a clothing article comprising a first film layer resistant to penetration by liquid water but permeable to water vapor. The first film layer is adhered at discrete securement locations to a second layer of water vapor permeable extendable sheet material. The adherence between the two layers is such that when the composite material is under no stretching force and resting on a flat surface the second layer is corrugated, ruched or puckered. The adherence is also such that the composite material can be stretched at least 10% in at least one direction by a force less than that required to stretch the material forming the first layer by the same amount by itself. The preferred material of this invention also relies on a single microporous film layer for breathability and waterproofness. Waterproofness of such microporous films are typically low and they are commonly susceptible to loss in the waterproofness due to contamination of the micropores by low surface tension liquids like oils, perspiration, etc. Also, such films are air permeable and are not absolute barriers because of their microporous nature.
U.S. Pat. No. 4,761,324 (Rautenberg et.al.) describes a laminated elastic fabric which includes a layer of stretch material having substantial elastic qualities, a polymer film layer being breathable, water-resistant and having elastic qualities, and an adhesive present in substantially discontinuous segments bonding the film to the elastic fabric. The material of this invention also relies on a single layer of polymer film for the properties of waterproofness and breathability. If such films are non-porous, they must be hydrophilic for adequate breathability. In that case, the hydrophilic nature of the film will cause them to swell and weaken significantly when in contact with liquid water. As a result, such polymer films usually show poor durability particularly when subjected to repeated automatic machine washing. U.S. Pat. No. 5,036,551 (Dailey et.al.) describes elastomeric composite fabrics which have a layered construction and are made of a microporous polymeric membrane, a water vapor permeable polymer, and an elastomeric thermoplastic nonwoven material. The elastomeric composite fabric provides barrier properties with water vapor permeability and finds utility in articles of wearing apparel and other articles which conform to the wearer. The material of this invention may not be suitable for certain end-uses since it uses an elastic non-woven material as a support which is relatively weaker than conventional woven or knitted fabrics. Also, the nonwoven material is bonded by using a continuous layer of a hydrophilic polyurethane which is susceptible to swelling and weakening in wet environments and is likely to contribute to poor durability in end-uses demanding repeated exposure to wet environments and automatic machine wash.
U.S. Pat. No. 4,443,511 (Worden et.al.) describes a waterproof and breathable elastomeric polytetrafluoroethylene layered article for use in, for example, material for protective articles. The waterproof and breathable polytetrafluoroethylene layered article can, for example, exhibit elastomeric properties of stretch to break of 275% in the machine direction and 145% in the transverse direction and a total stretch recovery of at least 39% after being stretched to 75% extension for 100 cycles. The invention further provides a waterproof and breathable polytetrafluoroethylene layered article bonded to a stretch fabric. The waterproof and breathable elastomeric polytetrafluoroethylene layered article bonded to a stretch fabric is thus durable and possesses a water vapor transmission rate exceeding 1000 gms./m.sup.2 day, and preferably above about 2000 gms/m.sup.2 day. The material of this invention may not possess adequate stretch recovery properties for certain end uses.